Update: Mass Spec (MS) – Fixed; Computer – Broken
We have deiced to move on to a new method of analysis for our fingerprints. We are now using a Gas Chromatography Mass Spectrometer (GC-MS), which has its ups and downs. The amount of time that it take to run each sample has increased from 15 minutes to 40 minutes however, it can give us more accurate results. Using the MS we were required to make our own prediction of the compounds based of their molecular weight however, using the GC-MS the instrument is capable of searching through a library to identify the actual presence of a specific compound.
We have run a few test samples to get used to the new machine, and plan to begin as soon as possible with our fingerprint samples. Since we are in a position to identify the components of the fingerprints more easily, we will be able to make up for lost time from waiting for the instrument to be fixed. With our project finally running smoothly again I am looking forward to present our final findings in April.
Unfortunately, since October our research has run into many roadblocks. It began when I failed to properly save a days worth of work, meaning I had to rerun all the samples I had gotten through again the following week. However, when the next week finally rolled around to our dismay we found that the Mass Spectrometer would not run. Instead we received error messages telling use to “Please reconfigure your hardware before opening a method.” After riffling through the instruction manual and many phone calls to the company we decrypted the message. Simply put, our machine was no long speaking to the computer.
All hope was not lost though, We had the data from previous tests and we had also sent duplicates of the samples to ThermoFisher Scientific for them to run tests using a newer model, the ThermoFisher Scientific Q executive plus. With the more precise break down of composition we were able to confirm which of our peaks were true and which were background noise.
Comparing the same sample across both methods we were able to identify at least five peaks represented in both. From those peaks it appears that at least one is cause by the use of ethanol as a solvent while the others may natural components of fingerprint oils. Additionally, we were able to see that certain peaks are a common occurrence in almost of the samples.
Updates on the Mass Spectrometer to come.
Each person’s fingerprints are unique solely to them; because of this fingerprints are one of the best forms of identification. A latent fingerprint is an impression left on a surface. It comprises of a pattern of ridges and furrows from the human finger. Getting a fingerprint that is suitable for identification is not always possible; in some situations the print may be incomplete or smeared. The eccrine, apocrine, and sebaceous glands are found on the surface on human skin. These three glands contribute to the composition of oils that make up a human fingerprint. The lipid composition of these oils may be a determinant for identification. We propose that spectrometry can be used to identify an individual based off the lipid composition of their fingerprints.
From this research we hope to determine if the lipid composition of an individual stays consistent over time and if it is specific only to them. To test this we will collect fingerprint samples from volunteers; to do this we will rinsing each fingertip on one hand with ethanol and save the solution. We will also have each volunteer fill out a brief questionnaire. From here we will run each saved sample through the mass spectrometer and evaluate its composition. Once this is complete for each individual, we will compare the results of the paired samples and questionnaires to determine if factors such as one’s or gender or diet contribute to the composition or if it is independent of these factors. Finally we will compare the samples to determine if mass spectrometry is a valid method of identifying an individual.